GLONASS: Dispelling the myths around Russia’s GPS

Aleksandr Gurko: "In Russia the dual GLONASS/GPS navigation system is accepted as the state standard, that is to say it is compulsory for all state applications and for ensuring security." Source: RIA Novosti

While everyone in Russia has heard the name GLONASS, the satellite navigation system, few Russian high-tech start-ups have attracted as many rumors, misapprehensions and even jokes.

Aleksandr Gurko, the president of
the non-commercial partnership GLONASS, attempts to dispel some of the myths
surrounding this system in an interview with RIA Novosti.

Why do we need GLONASS if the
whole world is using global positioning system (GPS)?

A user can solve the same problem — that of finding their location on a map by using signals from both GLONASS
and GPS. The Russian and American systems are on a par. There is no motivation
for the customer to simply exchange one system for another.

Related:

The situation is changing if
equipment is used that is able to receive and process signals from both
systems. Moreover the user gains a significant advantage both in terms of the
speed at which the coordinates are processed and their reliability: for
‘standard’ urban conditions this increases from 60 percent to 70percent up to
the maximum of practically 100 percent.

In this case the operator of the
navigation system — for GPS this was and remains the Pentagon—has the option of
either switching off the civilian signal for a specific area or of desensitizing
it artificially.

The latest generation of GPS satellites also supports this
function. This is not even about military conflict, as the threat of turning
off the navigation switch can in itself be used to achieve political or
economic aims. Therefore it is just a small step from a technological
dependence on a narrow satellite navigation field to economic, political and
military dependence.

The critically important
infrastructure that the entire world uses and on which a significant portion of
the national economy is based should not be reliant on one country. In Russia
the dual GLONASS/GPS navigation system is accepted as the state standard, that
is to say it is compulsory for all state applications and for ensuring security.

Russia has claimed more than once
that GLONASS is the only alternative to GPS. How does this correspond to
reality?

This is true today. The situation,
though, will change in the course of the next three to four years. The Chinese
BeiDou system at the moment operates as a regional system (that is to say it
supplements GLONASS and GPS) within the limits of the Asia-Pacific region.

The
European Union has begun to deploy the Galileo system. In the absence of some
kind of force majeure, both these systems will be deployed globally in the next
few years.

This however is the problem for
the pioneers. Both GPS and GLONASS were developed in the 1970s, and they do not
take into consideration all the modern technology. Galileo and especially
BeiDou were designed decades later, which allowed more modern and more
technically advanced systems to be developed.

The GPS and GLONASS systems are
being modernized but this process takes longer and is more expensive in as much
as operational orbiting satellites have to be gradually replaced with newer
models.

It is often said that GPS is
significantly more accurate than GLONASS. Is there any truth in this?

GLONASS’ actual user accuracy is
conceding now on average to GPS. If a GPS receiver can theoretically fix a
position in an exposed location to within no more than 3 meters to 4 meters,
for GLONASS this figure is within 7 meters to 10 meters.

This theoretical difference is
not important in practice for two reasons. The first being that there are no
receivers that support just GLONASS and not GPS, and the second is that the
client’s receiver will normally carry out additional signal processing,
averaging out the result.

For example if a car travels along a perfectly
straight road the trajectory of the vehicle’s motion in terms of satellite
navigation data would look like a fairly intricately broken line, with a large
number of random deviations. In this case the system’s software fixes this line
onto a digital map and as a result the screen displays the self same perfectly
straight road that exists in reality.

How can the accuracy of GLONASS
be improved?

Positioning accuracy can be
improved with the help of both satellite and ground based infrastructure.

Today a wide-area augmentation
(Sistema Shirokozonnoy Differentsialnoy Korrektsii, or SDKM) system is being
developed in Russia. Corrections will be sent to the SDKM via a satellite
communication channel from Luch satellites in geostationary orbit.

The accuracy
of the coordinates will increase to decimeters. But the user (should anyone
require that sort of accuracy) will need to fit special modems, which are able
to pick up the satellite signal.

There is an alternative - without
a satellite, but for this you would need around 300 differential correction
base stations located in the most developed corners of the country. This
variant could ensure millimeter accuracy for a fraction of the cost.